Non-freezing storage unit and refrigerator including the same

ABSTRACT

The present invention relates to a non-freezing storage unit which can store food at a temperature below 0° C. without freezing the food, and a refrigerator including the same. The non-freezing storage unit includes an outer casing with one open surface, a drawer which can be pulled out and detached through the open surface of the outer casing, a sensor located on one surface of the outer casing and sensing a temperature of food located in the drawer, a thermal conductive member installed on one surface of the drawer facing the sensor and transferring the temperature of the food in the drawer to the sensor, and a heater installed in the outer casing. The non-freezing storage unit is located in a cooling space to store food in a non-frozen state at a temperature below 0° C.

TECHNICAL FIELD

The present invention relates to a non-freezing storage unit which can store food at a temperature below 0° C. without freezing the food, and a refrigerator including the same.

BACKGROUND ART

Supercooling means the phenomenon that a molten object or a solid is not changed although it is cooled to a temperature below a phase transition temperature in an equilibrium state. A material has a stable state at every temperature. If the temperature is slowly changed, the constituent elements of the material can follow the temperature changes, maintaining the stable state at each temperature. However, if the temperature is suddenly changed, since the constituent elements cannot be changed into the stable state at each temperature, the constituent elements maintain a stable state at an initial temperature, or some of the constituent elements fail to be changed into a state at a final temperature.

For example, when water is slowly cooled, it is not temporarily frozen at a temperature below 0° C. However, when water enters a supercooled state, it has a kind of quasi-stable state. As this unstable equilibrium state is easily broken even by slight stimulation, water tends to move into a more stable state. That is, if a small piece of the material is put into the supercooled liquid, or if the liquid is suddenly shaken, the liquid starts to be frozen at once such that the temperature of the liquid reaches the freezing point, and maintains a stable equilibrium state at the temperature. In general, an electrostatic atmosphere is made in a refrigerator, and meat and fish are thawed in the refrigerator at a minus temperature. In addition to the meat and fish, fruit is kept fresh in the refrigerator.

This technology uses a supercooling phenomenon. The supercooling phenomenon indicates the phenomenon that a molten object or a solid is not changed although it is cooled to a temperature below a phase transition temperature in an equilibrium state.

This technology includes Korean Patent Publication No. 2000-0011081 which discloses an electrostatic field processing method, an electrostatic field processing apparatus, and electrodes therefor.

FIG. 1 is a view of an example of a conventional thawing and freshness-keeping apparatus. A keeping-cool room 1 is composed of an insulation material 2 and an outer wall 5. A mechanism (not shown) controlling a temperature inside the room 1 is installed therein. A metal shelf 7 installed in the room 1 has a two-layer structure.

Target objects to be thawed or freshness-kept and ripened such as vegetables, meat and marine products are loaded on the respective layers. The metal shelf 7 is insulated from the bottom of the room 1 by an insulator 9. In addition, since a high voltage generator 3 can generate 0 to 5000 V of DC and AC voltages, an insulation plate 2 a such as vinyl chloride, etc. is covered on the inside of the insulation material 2. A high-voltage cable 4 outputting the voltage of the high voltage generator 3 is connected to the metal shelf 7 after passing through the outer wall 5 and the insulation material 2.

When a user opens a door installed at the front of the keeping-cool room 1, a safety switch 13 (see FIG. 2) is turned off to intercept the output of the high voltage generator 3.

FIG. 2 is a circuit view of the circuit configuration of the high voltage generator 3. 100 V of AC is supplied to a primary side of a voltage regulation transformer 15. Reference numeral 11 represents a power lamp and 19 a working state lamp. When the door 6 is closed and the safety switch 13 is on, a relay 14 is operated. This state is displayed by a relay operation lamp 12. Relay contact points 14 a, 14 b and 14 c are closed by the operation of the relay 14, and 100 V of AC is applied to the primary side of the voltage regulation transformer 15.

The applied voltage is regulated by a regulation knob 15 a on a secondary side of the voltage regulation transformer 15, and the regulated voltage value is displayed on a voltmeter. The regulation knob 15 a is connected to a primary side of a boosting transformer 17 at the secondary side of the voltage regulation transformer 15. The boosting transformer 17 boosts the voltage at a ratio of 1:50. For example, when 60 V of voltage is applied, it is boosted to 3000 V.

One end O₁ of the output of the secondary side of the boosting transformer 17 is connected to the metal shelf 7 insulated from the keeping-cool room 1 through the high-voltage cable 4, and the other end O₂ of the output is grounded. Moreover, since the outer wall 5 is grounded, if the user touches the outer wall 5 of the keeping-cool room 1, he/she does not get an electric shock. Further, in FIG. 1, when the metal shelf 7 is exposed in the room 1, it should be maintained in an insulated state in the room 1. Thus, the metal shelf 7 needs to be separated from the wall of the room 1 (the air performs an insulation function). Furthermore, if a target object 8 is protruded from the metal shelf 7 and brought into contact with the wall of the room 1, the current flows to the ground through the wall of the room 1. Therefore, the insulation plate 2 a is attached to the inner wall to prevent drop of the applied voltage. Still furthermore, when the metal shelf 7 is covered with vinyl chloride without being exposed in the room 1, an electric field atmosphere is produced in the entire room 1.

In the prior art, an electric field or magnetic field is applied to the received object to be cooled such that the received object reaches a supercooled state. Accordingly, a complicated apparatus for producing the electric field or magnetic field should be provided to keep the received object in the supercooled state, and the power consumption is increased during the production of the electric field or magnetic field. Additionally, the apparatus for producing the electric field or magnetic field should further include a safety device (e.g., an electric field or magnetic field shielding structure, an interception device, etc.) for protecting the user from high power, when producing or intercepting the electric field or magnetic field.

DISCLOSURE Technical Problem

An object of the present invention is to provide a non-freezing storage unit in which a drawer can be completely pulled out of an outer casing.

Another object of the present invention is to provide a non-freezing storage unit which can maintain a received object in a supercooled state via power supply in a space where only the cooling is performed.

A further object of the present invention is to provide a non-freezing storage unit which can selectively perform the supercooled state control and the frozen state control on a received object.

A still further object of the present invention is to provide a non-freezing storage unit which can accomplish the convenience of the reception of a received object and the accurate sensing of a temperature of the received object.

A still further object of the present invention is to provide a non-freezing storage unit in which a control unit performing the supercooled state control and the frozen state control is separated from a receiving space of a received object and mounted on a side surface of the unit.

A still further object of the present invention is to provide a temperature change room in which the cooling/heating can be switched using a thermoelectric element, although an evaporator is not additionally included in a refrigerator.

A still further object of the present invention is to provide a temperature change room which can serve as a non-freezing room which can store food in a non-frozen supercooled state by adjusting a temperature of a thermoelectric element.

Technical Solution

According to an aspect of the present invention, there is provided a non-freezing storage unit, including: an outer casing with one open surface; a drawer which can be pulled out and detached through the open surface of the outer casing; a sensor located on one surface of the outer casing and sensing a temperature of food located in the drawer; a thermal conductive member installed on one surface of the drawer facing the sensor and transferring the temperature of the food in the drawer to the sensor; and a heater installed in the outer casing, wherein the non-freezing storage unit is located in a cooling space to store food in a non-frozen state at a temperature below 0° C. In addition, an insulation material is filled in the outer casing.

Moreover, the thermal conductive member includes a metal plate located on a bottom surface of the drawer and receiving a temperature change of the food, and a contact point portion transferring the temperature change between the metal plate and the sensor.

Further, the contact point portion is downwardly protruded from the bottom surface of the drawer.

Furthermore, a handle for use in pulling the drawer out is provided on one surface of the drawer corresponding to the open surface of the outer casing. Still furthermore, the handle includes a grip portion and a hook portion moved in cooperation with the grip portion, and the outer casing includes a hooked portion on which the hook portion is hooked.

Still furthermore, a gasket for use in sealing up the inner space is provided on one surface of the drawer corresponding to the open surface of the outer casing.

Still furthermore, the outer casing and the drawer include guide portions for guiding the movement of the drawer, respectively, and the guide portions guide the drawer so that the drawer can be located lower in the outer casing than during the movement, when the drawer is completely inserted into the outer casing.

Still furthermore, when the drawer is inserted into the outer casing and downwardly moved by the guide portions, the sensor and the thermal conductive member are brought into contact with each other.

Still furthermore, the non-freezing storage unit further includes a fan installed in the outer casing and producing the flow of the air in the unit.

Still furthermore, the heater includes an upper heater installed on an inside top surface of the outer casing and a lower heater installed on an inside bottom surface of the outer casing.

Still furthermore, the non-freezing storage unit further includes a sensor for sensing a temperature in the unit which is installed at an upper portion of the outer casing and senses a temperature of the air in the drawer.

Still furthermore, a heating value of the upper heater is adjusted according to the temperature measured by the sensor for sensing the temperature in the unit, and a heating value of the lower heater is adjusted according to the temperature measured by the sensor.

Still furthermore, the heating values of the upper heater and the lower heater are controlled so that the temperature in the inside upper portion of the unit can be higher than the temperature in the inside lower portion of the unit by about 1 to 2° C.

Still furthermore, at least one of the upper heater and the lower heater includes a plurality of individual heaters, at least one of the plurality of individual heaters is constantly operated, and the other individual heaters are turned on/off according to the temperature in the unit.

Still furthermore, the non-freezing storage unit further includes a side casing located on a side surface of the outer casing and having a display portion and a button portion at the front.

Still furthermore, the non-freezing storage unit further includes a control panel installed in the side casing, cooperating with the display portion, the button portion and the sensor, and controlling electric components in the unit.

Still furthermore, the heater is a thermoelectric element having the flowing current and voltage controlled to adjust the temperature in the non-freezing storage unit.

Meanwhile, there is provided a refrigerator, including: a non-freezing storage unit described above; and a cooling space cooled by a freezing cycle and having the non-freezing storage unit therein.

In addition, a temperature in the non-freezing storage unit is maintained at about −2° C. to −4° C., raised to normal temperature when it is determined that the food has been frozen on the basis of a food temperature change sensed by a sensor, and lowered again to −2° C. to −4° C. to store the food.

Advantageous Effects

According to the temperature change room of the refrigerator of the present invention, the temperature change room is implemented using the thermoelectric element. Therefore, when it is intended to store the food at a temperature lower than a temperature in a refrigerating chamber, it is not necessary to introduce the cool air of a freezing chamber into the temperature change room. A damper or the like is not necessary, which simplifies the structure of the refrigerator.

In addition, according to the temperature change room of the refrigerator of the present invention, the heating can be performed in the temperature change room using the thermoelectric element. It is thus not necessary to install two or more evaporators to utilize a heating function.

Moreover, according to the temperature change room of the refrigerator of the present invention, the temperature in the temperature change room can be adjusted regardless of the operation conditions of the refrigerating chamber and the freezing chamber.

Further, according to the non-freezing storage unit provided by the present invention, the drawer can be completely detached from the outer casing, which improves the convenience of the use.

Furthermore, according to the non-freezing storage unit provided by the present invention, the sensor is installed in the outer casing and more sensitively senses the temperature of the food. This improves the non-freezing stability and enables easy determination on the release of the non-frozen state.

Still furthermore, according to the non-freezing storage unit provided by the present invention, the operation panel and the control panel irrelevant to the refrigerator are installed at one side of the non-freezing storage unit to thereby easily control the functions of the non-freezing storage unit.

Still furthermore, according to the non-freezing storage unit provided by the present invention, the plurality of heaters are provided to perform the non-freezing function. In a state where one or more heaters are always in operation, the other heaters are used to adjust the heating value. It is thus possible to reduce the temperature fluctuation range in the non-freezing storage unit influenced by the adjustment of the heating value of the heater. It is also possible to reduce the influence on the sensor exerted by the change in the heating value of the heater. This improves the sensitivity of the sensor to the release of the non-frozen state.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view of an example of a conventional thawing and freshness-keeping apparatus.

FIG. 2 is a circuit view of the circuit configuration of a high voltage generator.

FIG. 3 is a view showing a process in which ice crystal nucleuses are formed in a liquid during the cooling.

FIG. 4 is a view showing a process of preventing the ice crystal nucleus formation, which is applied to an apparatus for supercooling according to the present invention.

FIG. 5 is a schematic configuration view of the apparatus for supercooling according to the present invention.

FIG. 6 is a graph showing a supercooled state of water in the apparatus for supercooling of FIG. 5.

FIG. 7 is an exploded perspective view of a non-freezing storage unit according to a first embodiment of the present invention.

FIG. 8 is a perspective view of the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 9 is a sectional view of the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 10 is a view of a metal plate installed in a drawer of the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 11 is a view showing a state where the metal plate is installed in the drawer of the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 12 is a view showing a process in which the drawer of the non-freezing storage unit of the present invention is inserted into an outer casing.

FIG. 13 is a view showing a state where a contact point portion and a sensor installation portion of the non-freezing storage unit of the present invention are in contact with each other.

FIG. 14 is an exploded perspective view of a front portion of the drawer included in the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 15 is an exploded perspecrive view of a side casing provided in the non-freezing storage unit according to the first embodiment of the present invention.

FIG. 16 is a graph showing food temperature changes sensed by sensors, when a box fan is not installed.

FIG. 17 is a graph showing food temperature changes sensed by the sensors, when the box fan is installed.

FIGS. 18 to 20 are views of a non-freezing storage unit of a refrigerator according to a second embodiment of the present invention.

FIG. 21 is a view of a refrigerator including the non-freezing storage unit according to the first or second embodiment of the present invention.

FIG. 22 is a side-sectional view of the refrigerator including the non-freezing storage unit according to the first or second embodiment of the present invention.

FIGS. 23 and 24 are views of a non-freezing storage unit according to a third embodiment of the present invention and a refrigerator including the same.

MODE FOR INVENTION

Hereinafter, the present invention will be described in detail with reference to the exemplary embodiments and the accompanying drawings.

FIG. 3 is a view showing a process in which ice crystal nucleuses are formed in a liquid during the cooling. As illustrated in FIG. 3, a container C containing a liquid L (or a received object) is cooled in a storing unit S with a cooling space therein.

For example, it is assumed that a cooling temperature in the cooling space is lowered from a normal temperature to a temperature below 0° C. (a phase transition temperature of water) or a temperature below a phase transition temperature of the liquid L. While the cooling is carried out, it is intended to maintain a supercooled state of the water or the liquid L (or the received object) at a temperature below the maximum ice crystal formation zone (−1° C. to −7° C.) of the water in which the formation of ice crystals is maximized, or at a cooling temperature below the maximum ice crystal formation zone of the liquid L.

The liquid L is evaporated during the cooling such that vapor W1 is introduced into a gas Lg (or a space) in the container C. In a case where the container C is closed, the gas Lg may be supersaturated due to the evaporated vapor W1.

When the cooling temperature reaches or exceeds a temperature of the maximum ice crystal formation zone of the liquid L, the vapor W1 forms ice crystal nucleuses F1 in the gas Lg or ice crystal nucleuses F2 on an inner wall of the container C. Alternatively, the condensation occurs in a contact portion of the surface Ls of the liquid L and the inner wall of the container C (almost the same as the cooling temperature in the cooling space) such that the condensed liquid L may form ice crystal nucleuses F3 which are ice crystals.

For example, when the ice crystal nucleuses F1 in the gas Lg are lowered and infiltrated into the liquid L through the surface Ls of the liquid L, the liquid L is released from the supercooled state and caused to be frozen. That is, the supercooling of the liquid L is released.

Alternatively, as the ice crystal nucleuses F3 are brought into contact with the surface Ls of the liquid L, the liquid L is released from the supercooled state and caused to be frozen.

As described above, according to the process of forming the ice crystal nucleuses F1 to F3, when the liquid L is stored at a temperature below its maximum ice crystal formation zone, the liquid L is released from the supercooled state due to the freezing of the vapor evaporated from the liquid L and existing on the surface Ls of the liquid L and the freezing of the vapor on the inner wall of the container C adjacent to the surface Ls of the liquid L.

FIG. 4 is a view showing a process of preventing the ice crystal nucleus formation, which is applied to an apparatus for supercooling according to the present invention.

In FIG. 4, to prevent the freezing of the vapor W1 in the gas Lg, i.e., to continuously maintain the vapor W1 state, the energy is applied to at least the gas Lg or the surface Ls of the liquid L so that the temperature of the gas Lg or the surface Ls of the liquid L can be higher than a temperature of the maximum ice crystal formation zone of the liquid L, more preferably, the phase transition temperature of the liquid L. In addition, to prevent the freezing although the surface Ls of the liquid L is brought into contact with the inner wall of the container C, the temperature of the surface Ls of the liquid L is maintained higher than a temperature of the maximum ice crystal formation zone of the liquid L, more preferably, the phase transition temperature of the liquid L.

Accordingly, the liquid L in the container C maintains the supercooled state at a temperature below its phase transition temperature or a temperature below its maximum ice crystal formation zone.

Moreover, when the cooling temperature in the storing unit S is a considerably low temperature, e.g., −20° C., although the energy is applied to an upper portion of the container C, the liquid L which is the received object may not be able to maintain the supercooled state. There is a need that the energy should be applied to a lower portion of the container C to some extent. When the energy applied to the upper portion of the container C is relatively larger than the energy applied to the lower portion of the container C, the temperature in the upper portion of the container C can be maintained higher than the phase transition temperature or a temperature of the maximum ice crystal formation zone. Further, the temperature of the liquid L in the supercooled state can be adjusted by the energy applied to the lower portion of the container C and the energy applied to the upper portion of the container C.

The liquid L has been described as an example with reference to FIGS. 3 and 4. In the case of a received object containing a liquid, when the liquid in the received object is continuously supercooled, the received object can be kept fresh for an extended period of time. The received object can be maintained in a supercooled state at a temperature below the phase transition temperature via the above process. Here, the received object may include meat, vegetable, fruit and other food as well as the liquid.

Furthermore, the energy adopted in the present invention may be thermal energy, electric or magnetic energy, ultrasonic energy, light energy, and so on.

FIG. 5 is a schematic configuration view of the apparatus for supercooling according to the present invention.

The apparatus for supercooling of FIG. 5 includes a case Sr mounted in the storing unit S in which the cooling is performed and having a receiving space therein, a heating coil H1 mounted on the inside of a top surface of the case Sr and generating heat, a temperature sensor C1 sensing a temperature in an upper portion of the receiving space, a heating coil H2 mounted on the inside of a bottom surface of the case Sr and generating heat, and a temperature sensor C2 sensing a temperature in the lower portion of the receiving space or a temperature of a received object P.

The apparatus for supercooling is installed in the storing unit S such that the cooling is performed therein. The temperature sensors C1 and C2 sense the temperature and the heating coils H1 and H2 are turned on to supply heat from the upper and lower portions of the receiving space to the receiving space. The heat supply quantity is adjusted to control the temperature in the upper portion of the receiving space (or the air on the received object P) to be higher than a temperature of the maximum ice crystal formation zone, more preferably, the phase transition temperature.

The positions of the heating coils H1 and H2 in FIG. 5 are appropriately determined to supply the heat (or energy) to the received object P and the receiving space. The heating coils H1 and H2 may be inserted into side surfaces of the case Sr.

FIG. 6 is a graph showing the supercooled state of water in the apparatus for supercooling of FIG. 5. The graph of FIG. 6 is a temperature graph when the liquid L is water and the principle of FIGS. 4 and 5 is applied thereto.

As illustrated in FIG. 6, line I represents a curve of the cooling temperature in the cooling space, line II represents a curve of the temperature of the gas Lg (air) on the surface of the water in the container C or the case Sr (or the temperature in the upper portion of the container C or the case Sr), and line III represents a curve of the temperature in the lower portion of the container C or the case Sr. A temperature of an outer surface of the container C or the case Sr is substantially identical to the temperature of the water in the container C or the case Sr.

As shown, in a case where the cooling temperature is maintained at about −19° C. to −20° C. (see line I), when the temperature of the gas Lg on the surface of the water in the container C is maintained at about 4° C., to 6° C. which is higher than a temperature of the maximum ice crystal formation zone of the water, the temperature of the water in the container C is maintained at about −11° C. which is lower than a temperature of the maximum ice crystal formation zone of the water, but the water is stably maintained in a supercooled state which is a liquid state for an extended period of time. Here, the heating coils H1 and H2 supply heat.

Additionally, in FIG. 6, the energy is applied to the surface of the water or the gas Lg on the surface of the water before the temperature of the water reaches a temperature of the maximum ice crystal formation zone, more preferably, the phase transition temperature due to the cooling. Thus, the water stably enters and maintains the supercooled state.

FIG. 7 is an exploded perspective view of a non-freezing storage unit according to a first embodiment of the present invention, FIG. 8 is a perspective view of the non-freezing storage unit according to the first embodiment of the present invention, and FIG. 9 is a sectional view of the non-freezing storage unit according to the first embodiment of the present invention.

The non-freezing storage unit according to the first embodiment of the present invention roughly includes an outer casing 100, a drawer 200 and a side casing 300. The drawer 200 can be inserted into and pulled out of the outer casing 100. As any separate electronic device is not attached to the drawer 200, the drawer 200 can be completely separated and detached from the outer casing 100. The outer casing 100 includes an insulation material 110 to insulate the non-freezing storage unit from the other region of a refrigerator in which the non-freezing storage unit is located. The drawer 200 and the side casing 300 also include insulation materials 210 and 310, respectively. It is thus possible to insulate the portions which are not sufficiently insulated by the insulation material 110 of the outer casing 100. Heaters 140 are installed on the inside of the outer casing 100. A control unit (not shown) adjusts heating values of the heaters 140 to control a temperature in the non-freezing storage unit. The heaters 140 include an upper heater 142 and a lower heater 144, and the control unit (not shown) control the heating values of the upper heater 142 and the lower heater 144, respectively. In addition, a sensor 132 for sensing a temperature in the unit which measures the temperature in the non-freezing storage unit is installed on the upper side of the outer casing 100. In order to minimize the influence on the sensor 132 for sensing the temperature in the unit exerted by the heat of the heaters 140, the heaters 140 may not be located adjacent to the sensor 132 for sensing the temperature in the unit, and a separate insulation member (not shown) may be further installed between the heaters 140 and the sensor 132 for sensing the temperature in the unit. Moreover, sensors 134 and 136 sensing a temperature of food are provided on the lower side of the outer casing 100. The sensors 134 and 136 measure the temperature of the food located in the drawer 200. Preferably, a plurality of sensors 134 and 136 are installed at given intervals to reflect the temperature of the food to the operation of the non-freezing storage unit, when the food is widely distributed in the drawer 200. In this embodiment, although two sensors 134 and 136 are installed, three or more sensors may be installed. As the sensors 134 and 136 are not installed in the drawer 200 brought into contact with the food but in the outer casing 100, a cable for use in transferring power to the sensors 134 and 136 and receiving temperature sensing information therefrom can be removed from the drawer 200. There is an advantage in that the drawer 200 can be completely pulled out of the outer casing 100. If the drawer 200 is not completely pulled out of the outer casing 100, it is inconvenient to put the food into the drawer 200 or take the food out of the drawer 200 and very difficult to clean the drawer 200. The sensors 134 and 136 are attached to bottom surfaces of sensor installation portions 134 a and 136 a of a thin metal plate attached to the bottom surface of the outer casing 100, and thus are not exposed to the outside of the outer casing 100.

FIG. 10 is a view of a metal plate installed in the drawer of the non-freezing storage unit according to the first embodiment of the present invention, and FIG. 11 is a view showing a state where the metal plate is installed in the drawer of the non-freezing storage unit according to the first embodiment of the present invention. As described above, in the non-freezing storage unit according to the first embodiment of the present invention, since the drawer 200 can be completely pulled out of the outer casing 100 and separated therefrom, the sensors 134 and 136 are not located in the drawer 200 but in the outer casing 200. There is a disadvantage in that the sensitivity of the sensors 134 and 136 sensing the temperature of the food stored in the drawer 200 may be reduced. To compensate for this, a metal plate 232 receiving a temperature change of the food distributed in the drawer 200, and contact point portions 234 and 236 transferring the temperature change of the metal plate 232 to the sensors 134 and 136 are provided in a basket 230 of the drawer 200. The contact point portions 234 and 236 are downwardly protruded from a bottom surface of the basket 230. When the drawer 200 is completely inserted into the outer casing 100, the sensor installation portions 134 a and 136 a and the contact point portions 234 and 236 are brought into contact without a gap, to thereby effectively transfer the temperature of the food to the sensors 134 and 136.

FIG. 12 is a view showing a process in which the drawer of the non-freezing storage unit of the present invention is inserted into the outer casing, and FIG. 13 is a view showing a state where the contact point portion and the sensor installation portion of the non-freezing storage unit of the present invention are in contact with each other. The drawer 200 included in the non-freezing storage unit according to the first embodiment of the present invention includes the contact point portions 234 and 236 downwardly protruded from the bottom surface of the basket 230. When the contact point portions 234 and 236 are in contact with the sensor installation portions 134 a and 136 a without a gap, the sensors 134 and 136 can sense the temperature of the food better. However, while the drawer 200 is moved in the outer casing 100, if the contact point portions 234 and 236 continuously cause the friction in contact with the outer casing 100, problems occur such as the abrasion of the contact point portions 234 and 236 and the outer casing 100, the noise caused by the friction, and an excessive force to push and pull the drawer 200. Accordingly, it is preferable that the contact point portions 234 and 236 should maintain a given interval from the bottom surface of the outer casing 100 when the drawer 200 is moved in the outer casing 100, and should be brought into contact with the sensor installation portions 134 a and 136 a when the drawer 200 is completely inserted into the outer casing 100. For this purpose, guide portions 120 and 220 (see FIG. 12) guiding the movement position of the drawer 200 in the outer casing 100 are provided in the corresponding positions of the outer casing 100 and the drawer 200, respectively.

The guide portions 120 and 220 include rails 122 and 222 and rollers 124 and 224, respectively. When the drawer 200 is inserted into the outer casing 100, the rollers 124 and 224 of the outer casing 100 and the drawer 200 are brought into contact with each other. Next, the rollers 224 of the drawer 200 roll over the rails 122 of the outer casing 100 and the rails 222 of the drawer 200 roll over the rollers 124 of the outer casing 100 at the same time such that the drawer 200 is inserted into the outer casing 100. The rails 122 of the outer casing 100 are inclined to the lower portion so that the drawer 200 can be downwardly moved at the back of the outer casing 100. In order to prevent the rollers 224 of the drawer 200 from being separated from the rails 122 of the outer casing 100 due to the inclined portions, preferably, the rear portions of the rails 122 are blocked in a width to accommodate the rollers 224. Additionally, to prevent the interference between the drawer 200 and the rollers 124 of the outer casing 100 when the drawer 200 is downwardly moved at the back of the outer casing 100, stepped portions are formed at the front of the rails 222 of the drawer 200 to accommodate the rollers 124 of the outer casing 100. Therefore, referring to the drawings, while the drawer 200 is inserted into the outer casing 100 and moved therein, the contact point portions 234 and 236 can be moved without any interference and friction, maintaining a given interval from the bottom surface of the outer casing 100. Moreover, after the drawer 200 is completely inserted into the outer casing 100, the drawer 200 is downwardly moved by the guide portions 120 and 220 and the contact point portions 234 and 236 are completely in contact with the sensor installation portions 134 a and 136 a.

FIG. 14 is an exploded perspective view of a front portion of the drawer included in the non-freezing storage unit according to the first embodiment of the present invention. Referring to FIGS. 7 and 14, the front portion of the drawer 200 includes a front frame 240 defining the frame of the front portion of the drawer 200 and connected to the basket 230, a cover 250 covering the front of the front frame 240, a gasket 260 attached to the back of the front frame 240 and sealing up between the outer casing 100 and the drawer 200 when the drawer 200 is closed, a hook portion 272 fixing the outer casing 100 and the drawer 200 to be closely attached to each other when the drawer 200 is closed, an elastic member 274 applying an elastic force to the hook portion 272, and a grip portion 276 which can release a locked state of the hook portion 272. In addition, the insulation material 210 of the drawer 200 mentioned above is filled in the front frame 240.

When taking the drawer 200 out of the outer casing 100 or inserting the drawer 200 into the outer casing 100, a user can insert or take out the drawer 200 by holding the cover 250 portion. For the user's convenience, a handle 252 is formed at the cover 250 portion. Any shape of handle 252 may be used as far as it helps the user to easily take the drawer 200 out of the casing 100. However, for the convenience of the use, the handle 252 is formed in the shape of a groove on the lower side of the front surface of the cover 250 so that the user can release the locked state of the hook portion 272 and pull the drawer 200 out at the same time by gripping the grip portion 276. If the position of the grip portion 276 is changed, the position of the handle 252 may also be changed so that the user can grip the grip portion 276 and pull the drawer 200 out at the same time.

As set forth herein, the non-freezing storage unit should be certainly insulated from the other region of the refrigerator to stably maintain the non-frozen state of the food. Here, a portion in which heat exchange with the other region of the refrigerator or heat leakage probably occurs is a gap between the drawer 200 and the outer casing 100 located at the front.

Accordingly, in order to ensure the insulation of the drawer 200 and the outer casing 100, the gasket 260 is attached to a rear portion of the front frame 240 brought into contact with a front portion of the outer casing 100. The gasket 260 is made of an elastic material such as natural rubber or synthetic rubber and transformed between the drawer 200 and the outer casing 100 by a force applied from the drawer 200 and the outer casing 100, thereby sealing up the gap between the drawer 200 and the outer casing 100.

As described above, when the drawer 200 is completely inserted into the outer casing 100, the drawer 200 is downwardly guided by the guide portions 120 and 220 (see FIG. 11). Since the guide portions 120 and 220 (see FIG. 11) are inclined at the back, the drawer 200 receives a force in the rearward and downward directions due to the self weight. Therefore, when the drawer 200 is completely inserted, the gasket 260 is transformed between the drawer 200 and the outer casing 100 due to the weight of the drawer 200 to seal up the gap. Moreover, the non-freezing storage unit according to the first embodiment of the present invention includes a hooked portion 172 and the hook portion 272 locking the outer casing 100 and the drawer 200 to enhance the sealing. To manipulate the hook portion 272, the grip portion 276 is located inside the handle 252 of the cover 250 and rotatably coupled to the front frame 240. When the user grips the grip portion 276 and holds the handle 252 with the grip portion 276, the grip portion 276 is rotated around coupling portions 276 a located at both sides of the grip portion 276 and coupled to the cover 250 such that an upper part of the grip portion 276 pushes a lower part of the hook portion 272. The hook portion 272 is also rotated around coupling portions 272 a coupled to the cover 250 such that an upper part of the hook portion 272 is lifted from the hooked portion 172 of the outer casing 100 and the coupling of the hook portion 272 and the hooked portion 172 is released. Thus, the user can pull the drawer 200 out of the outer casing 100. Here, the elastic member 274 with both ends fixed by the hook portion 272 and the cover 250 is provided so that the upper part of the hook portion 272 can be firmly fixed to the hooked portion 172 of the outer casing 100 in a normal situation, pressing the same. When the user grips the grip portion 276, the upper part of the hook portion 272 is lifted and the elastic member 274 is transformed, and when the user releases the grip portion 276, the upper part of the hook portion 272 is downwardly moved due to a restoring force of the elastic member 274. The outer casing 100 and the drawer 200 are fixed by the hook portion 272 and the hooked portion 172. This ensures the sealing between the outer casing 100 and the drawer 200. FIG. 15 is an exploded perspective view of the side casing provided in the non-freezing storage unit according to the first embodiment of the present invention.

The insulation material 310, a control panel (not shown), a control panel mounting portion 320, an operation panel (not shown) and an operation panel mounting portion 330 are installed in the side casing 300. The operation panel (not shown), which includes a button portion 315 a, 315 b, 315 c and 315 d enabling the input of functions of the non-freezing storage unit and a display portion 316 displaying the selected function, displays the function input through the button portion 315 a, 315 b, 315 c and 315 d on the display portion 316 and transmits information on the inputted function to the control panel (not shown). Preferably, a window (hole) is provided in a corresponding position of the side casing 300 to expose the button portion 315 a, 315 b, 315 c and 315 d and the display portion 316 of the PCB operation substrate to the outside. The button portion 315 a, 315 b, 315 c and 315 d and the display portion 316 are not located on the drawing 200 but on the side casing 300 such that the drawing 200 is completely detachable from the outer casing 100. The button portion 315 a, 315 b, 315 c and 315 d includes a button 315 a selecting a thin ice function, a button 315 b selecting a freezing function, a button 315 c selecting a supercooling function, and a button 315 d turning on and off power of the non-freezing storage unit. The display portion 316 displays the power-on/off state of the non-freezing storage unit and the function currently performed in the non-freezing storage unit. When the user turns on power of the non-freezing storage unit through the button 315 d and selects the thin ice function through the button 315 a, the control panel (not shown) receives an input signal from the button 315 a and displays that the refrigerating function has been selected through the display portion 316. In addition, the control panel (not shown) adjusts the heating values of the heaters 140 installed in the outer casing 100 (see FIG. 8) such that the temperature in the non-freezing storage unit ranges from about −5° C. to −8° C. The control panel (not shown) adjusts the heating values of the heaters 140 through the sensor 132 for sensing the temperature in the unit and the sensors 134 and 136 such that the temperature in the non-freezing storage unit exists in a desirable temperature range. For example, when the meat is stored in the non-freezing storage unit using the thin ice mode, it can be easily cut due to thin ices. Moreover, when the user selects the freezing function through the button 315 b, the control panel (not shown) turns off all the heaters 140 and stores the food at the same temperature as that of the other region of the refrigerator without separate temperature control. Meanwhile, when the user selects the non-freezing function through the button 315 c, the control panel (not shown) continuously senses the temperature in the non-freezing storage unit and the temperature of the food through the sensors 132, 134 and 136 and adjusts the heating values of the heaters 140 so that the temperature in the non-freezing storage unit can be maintained at about −2° C. to −4° C. When the meat or the like is stored at a temperature below 0° C. without being frozen by the non-freezing function, it is possible to prevent the taste from being reduced by the ice crystal formation in the meat and the destruction of fibers of the meat.

In addition, while the meat is stored in the non-freezing storage unit by the non-freezing function, its non-frozen state may be broken due to a shock or partial temperature unbalance. Even if ice crystals are formed in some part, the freezing may be easily spread to the entire meat. Once the freezing is started, the temperature is suddenly raised to near 0° C. which is the phase transition temperature. Therefore, when a sudden temperature change is sensed by the sensors 134 and 136, it is determined that the stored food such as the meat, etc. has been frozen. The food in the non-freezing storage unit is thawed, and then stored again in the non-frozen state. To thaw the food in the non-freezing storage unit, preferably, the temperature is raised to near normal temperature, at least 2° C. and maintained for a given time such that the food is sufficiently thawed and stored again in the non-frozen state. Moreover, when the user selects the non-freezing function, the control panel (not shown) may adjust the heating values of the heaters 140 via a given algorithm using the sensor 132 for sensing the temperature in the unit and the sensors 134 and 136 so that the temperature in the unit can be maintained at −2° C. to −4° C. However, the control panel (not shown) may adjust the heating value of the upper heater 142 merely using the temperature sensed by the sensor 132 for sensing the temperature in the unit such that the temperature in the upper portion of the non-freezing storage unit is maintained at about −2° C., and may adjust the heating value of the lower heater 144 merely using the temperature sensed by the sensors 134 and 136 such that the temperature in the lower portion of the non-freezing storage unit is maintained at about −3° C. to −4° C.

Meanwhile, a box fan (not shown) may be installed in one side of the inner space of the outer casing 100 (e.g., the rear portion of the outer casing) where there is no interference between the outer casing 100 and the drawer 200 or the inner space of the side casing 300 so as to produce the forcible flow in the non-freezing storage unit. If the box fan (not shown) is provided in the inner space of the side casing 300, a flow vent (not shown) should be further formed between the side casing 300 and the outer casing 100 so that the forcible flow caused by the box fan can be produced in the outer casing 100 in which the basket 230 is located. In a case where the box fan (not shown) is installed to produce the forcible flow, the temperature distribution in the non-freezing storage unit becomes uniform, and thus the sensitivity of the sensors 134 and 136 sensing the release of the non-frozen state is improved. FIG. 16 is a graph showing food temperature changes sensed by the sensors, when the box fan is not installed, and FIG. 17 is a graph showing food temperature changes sensed by the sensors, when the box fan is installed. Comparing the two graphs, when the box fan is not installed, the temperature measured by the sensors 134 and 136 is fluctuated in a small fluctuation range, but when the box fan is installed, the entire section is clearly divided into a section where the temperature fluctuation range is very small and a section where the temperature fluctuation range is very large. Accordingly, when the box fan (not shown) is installed, although the same sensors 134 and 136 are used, it is possible to control the heating values of the heaters 140 to maintain the supercooled state with high reliability, and to easily determine the release of the supercooling (i.e., the start of the freezing).

Further, each of the heaters 140, i.e., the upper heater 142 and the lower heater 144 may include a plurality of heaters. When the non-freezing storage unit performs the non-freezing function, the plurality of upper heaters 142 and lower heaters 144 are operated in a state where at least one heater is always on and the other heaters are on/off according to the temperature measured by the sensor 132 for sensing the temperature in the unit and the sensors 134 and 136. When the upper heater 142 and the lower heater 144 are composed of the plurality of heaters, respectively, the temperature fluctuation range in the unit influenced by the heating value of the heater is small compared with the on/off of a single heater. Thus, it is easy to distinguish the temperature fluctuation caused by the on/off of the heater from the temperature fluctuation caused by the release of the supercooling. Compared with a large temperature fluctuation range, a small temperature fluctuation range can improve the supercooling stability and the freshness of the food.

FIGS. 18 to 20 are views of a non-freezing storage unit of a refrigerator according to a second embodiment of the present invention. The non-freezing storage unit 100 according to the second embodiment, which is formed in the shape of a drawer, includes an outer casing 110 formed in the shape of a rectangular-parallelepiped and having one open surface (front surface), and a drawer 120 which can be pulled out and detached from the outer casing 110 through the open surface (the front surface in FIGS. 18 to 20) of the outer casing 110. The outer casing 110 is filled with an insulation material 113 to insulate the non-freezing storage unit 100 from a cooling space of the refrigerator such as a refrigerating chamber and a freezing chamber. The non-freezing storage unit 100 may be used at the same temperature as that of the refrigerating chamber and the freezing chamber, but is normally used at a specific temperature different from the operation conditions of the refrigerating chamber and the freezing chamber. When the temperature transfer does not occur between the non-freezing storage unit 100 and the refrigerating chamber or the freezing chamber, a loss caused by heat exchange can be minimized.

A thermoelectric element 111 is installed on the inside of the outer casing 110. According to the direction of the current applied to the thermoelectric element 111, the temperature is lowered at one side for cooling and raised at the other side for heating. In the non-freezing storage unit 100 of the present invention, the temperature in the non-freezing storage unit 100 is adjusted using the thermoelectric element 111, instead of using the general hotwire heater and the cool air of the refrigerating chamber or the freezing chamber. When it is intended to lower the temperature in the non-freezing storage unit 100, the direction of the current of the thermoelectric element 111 is adjusted to transfer the temperature change on the cooling side into the non-freezing storage unit 100, and when it is intended to raise the temperature in the non-freezing storage unit 100, the direction of the current of the thermoelectric element 111 is adjusted to transfer the temperature change on the heating side into the non-freezing storage unit 100. As the temperature in the non-freezing storage unit 100 is adjusted through the thermoelectric element 111, although the non-freezing storage unit 100 is installed in the refrigerating chamber, the temperature in the non-freezing storage unit 100 can be controlled to be lower than that of the refrigerating chamber. The non-freezing storage unit 100 further includes a conductor 112 which is in contact with the thermoelectric element 111 so that the temperature change of the thermoelectric element 111 can be evenly transferred into the non-freezing storage unit 100. Preferably, the conductor 112 is formed to cover the entire inner surface of the outer casing 110.

The relative installation positions of the outer casing 110, the thermoelectric element 111 and the conductor 112 will be described. The thermoelectric element 111 may be installed on the inner surface of the outer casing 110, and then the conductor 112 may be installed to cover the thermoelectric element 111. The temperature change on one side of the thermoelectric element 111 which is in contact with the conductor 112 is conducted through the conductor 112 and evenly transferred into the non-freezing storage unit 100, and the temperature change on the other side of the thermoelectric element 111 is insulated by the insulation material 113 of the outer casing 110 and prevented from being transferred into the refrigerating chamber or the freezing chamber in which the non-freezing storage unit 100 is located. One or plural thermoelectric elements 111 may be installed on the upper side of the inner surface of the outer casing 110, and one or plural thermoelectric elements 111 may be installed on the upper side and the lower side thereof, respectively. The thermoelectric element 111 is connected to a control unit (not shown), and the control unit (not shown) controls the direction and amplitude of the current flowing through the thermoelectric element 111 to maintain a set temperature input by a user or a temperature preset in the control unit (not shown).

For another example, the conductor 112 may be installed on the inner surface of the outer casing 110, and then the thermoelectric element 111 may be installed in contact with the conductor 112. Here, one side of the thermoelectric element 111 is in contact with the conductor 112 and the other side thereof is exposed in the non-freezing storage unit 100. As illustrated in FIG. 19, the area of one side of the thermoelectric element 111 exposed in the non-freezing storage unit 100 is larger than the area of the conductor 112 exposed in the non-freezing storage unit 100. Since the transfer of the temperature change is performed between the thermoelectric element 111 and the conductor 112 via conduction, it is performed at a very high speed. It is thus recognized that the temperature is almost the same in one side of the thermoelectric element 111 and the conductor 112. Since the area of the conductor 112 exposed in the non-freezing storage unit 100 is larger than the area of the thermoelectric element 111 exposed therein, the temperature in the non-freezing storage unit 100 is more influenced by the temperature change of the conductor 112, i.e., the temperature of one side of the thermoelectric element 111 which is in contact with the conductor 112 than the other side thereof exposed in the non-freezing storage unit 100. For example, when the non-freezing storage unit 100 is cooled, the direction of the current applied to the thermoelectric element 111 is adjusted so that one side of the thermoelectric element 111 which is in contact with the conductor 112 can be operated as the cooling side and the other side thereof exposed in the non-freezing storage unit 100 can be operated as the heating side. When the non-freezing storage unit 100 is used as a heating room, the direction of the current applied to the thermoelectric element 111 is adjusted in the opposite way. As the other side of the thermoelectric element 111 causing the temperature change in the opposite direction to the target direction of the temperature change of the non-freezing storage unit 100 is exposed, there is an advantage in that the temperature change slowly occurs in the non-freezing storage unit 100. When the other side of the thermoelectric element 111 is exposed in the non-freezing storage unit 100, if the non-freezing storage unit 100 is used to perform the general cooling and heating functions, since the cooling and heating switching time is long, a slight loss may be generated in terms of the energy efficiency. However, when the non-freezing storage unit 100 performs the non-freezing function of storing food at a temperature below 0° C. without freezing the food, since the temperature change slowly occurs, the stability in a given temperature region is excellent. This is a very good operation condition for forming the non-frozen state.

To perform the non-freezing function, the non-freezing storage unit 100 needs a sensor 114 which can measure the temperature inside the non-freezing storage unit 100 or the temperature of the stored food. Referring to FIGS. 18 and 19, the sensor 114 is installed on the lower side of the inner surface of the outer casing 110 to measure the temperature of the food. Although the sensor 114 is installed on the lower side of the inner surface of the outer casing 110 adjacent to the position of the food, it cannot accurately sense the temperature of the food. Therefore, it is preferable to provide a medium 124 transferring the temperature of the food to the sensor 114. The medium 124 is downwardly protruded from a bottom surface of the drawer 120 and brought into contact with the sensor 114. Meanwhile, to effectively transfer the temperature of the food located in the drawer 120 to the sensor 114, a conductor (not shown) is installed on the bottom surface of the drawer 120 which is in contact with the food. Preferably, the medium 124 is brought into contact with the conductor (not shown) and the sensor 114 to transfer the temperature (temperature change) from the conductor (not shown) to the sensor 114. In addition, preferably, the periphery of the sensor 114 is insulated by a sensor insulation material 115 such that the temperature sensing of the sensor 114 is less affected by the conductor 112. The sensor 114 receives power through a cable 114 a and transfers the sensed temperature information to the control unit (not shown). The control unit (not shown) controls the direction and intensity of the current applied to the thermoelectric element 111 according to the temperature information sensed by the sensor 114. With respect to the control unit (not shown), a separate control unit (not shown) irrelevant to a refrigerator main body may be provided in the outer casing 110 or the refrigerator main body to control the functions of the non-freezing storage unit 100, or a control unit (not shown) of the refrigerator main body may serve to control the functions of the non-freezing storage unit 100.

In the meantime, to control the functions of the non-freezing storage unit 100, operation portions 115 a, 115 b, 115 c and 115 d enabling the input of the functions and a display portion 116 displaying the working state of the non-freezing storage unit 100 are provided at the front of the non-freezing storage unit 100. Preferably, the operation portions 115 a, 115 b, 115 c and 115 d and the display portion 116 are not installed on the drawer 120 but on one side of the front of the outer casing 110 so that the drawer 120 can be completely detached from the outer casing 110. If a module is provided to wirelessly transmit and receive power and information between the outer casing 110 and the drawer 120, the operation portions 115 a, 115 b, 115 c and 115 d and the display portion 116 may be installed on the drawer 120, which increases the manufacturing costs.

The operation portions 115 a, 115 b, 115 c and 115 d include an operation portion 115 a selecting a refrigerating function, an operation portion 115 b selecting a heating function, an operation portion 115 c selecting a supercooling function, and an operation portion 115 d turning on and off power of the non-freezing storage unit 100. The display portion 116 displays the power-on/off state of the non-freezing storage unit 100 and the function currently performed in the non-freezing storage unit 100. When the user turns on power of the non-freezing storage unit 100 through the operation portion 115 d and selects the refrigerating function through the operation portion 115 a, the control unit (not shown) receives an input signal from the operation portion 115 a and displays that the refrigerating function has been selected through the display portion 116. In addition, the control unit (not shown) selects the direction of the current flowing to the thermoelectric element 111 through the cable 111 a so that the side of the thermoelectric element 111 which is in contact with the conductor 112 can be the cooling side. When the user selects the heating function through the operation portion 115 b, the control unit (not shown) selects the direction of the current flowing to the thermoelectric element 111 so that the side of the thermoelectric element 111 which is in contact with the conductor 112 can be the heating side. Moreover, when the user selects the non-freezing function through the operation portion 115 c, the control unit (not shown) selects the direction and amplitude of the current flowing to the thermoelectric element 111 so that the temperature in the non-freezing storage unit 100 can be maintained at about −2° C. to −4° C. For this purpose, the control unit (not shown) continuously senses the temperature of the food measured by the sensor 114 and appropriately controls the direction and amplitude of the current according to the sensed food temperature such that the temperature in the non-freezing storage unit 100 is maintained at about −2° C. to −4° C. When the meat or the like is stored at a temperature below 0° C. without being frozen by the non-freezing function, it is possible to prevent the taste from being reduced by the ice crystal formation in the meat and the destruction of fibers of the meat.

In the meantime, while the meat is stored in the non-freezing storage unit 100 by the non-freezing function, its non-frozen state may be broken due to a shock or partial temperature unbalance. Even if ice crystals are formed in some part, the freezing may be easily spread to the entire meat. Once the freezing is started, the temperature is suddenly raised to near 0° C. which is the phase transition temperature. Therefore, when a sudden temperature change is sensed by the sensor 114, it is determined that the stored food such as the meat, etc. has been frozen. The food in the non-freezing storage unit 100 is thawed, and then stored again in the non-frozen state. To thaw the food in the non-freezing storage unit 100, preferably, the temperature is raised to near normal temperature, at least 2° C. and maintained for a given time such that the food is sufficiently thawed and stored again in the non-frozen state.

FIG. 21 is a view showing an example in which the non-freezing storage unit according to the first or second embodiment of the present invention is applied to the conventional refrigerator. The refrigerator 1000 is divided into a freezing chamber 1100 and a refrigerating chamber 1200. The non-freezing storage unit 2000 is installed in the freezing chamber 1100. When the non-freezing storage unit 2000 is installed in the freezing chamber 1100, the cool air cooling the freezing chamber 1100 cools the periphery of the non-freezing storage unit 2000, and thus the meat in the non-freezing storage unit 2000 is stored at a low temperature. Generally, the temperature in the freezing chamber 1100 ranges from −8° C. to −18° C., which is lower than a temperature for storing the meat in a non-frozen state. However, the control panel (not shown) adjusts the heating values of the heaters 140 (see FIG. 9) via a given algorithm using the sensor 132 for sensing the temperature and the sensors 134 and 136 so that the temperature in the non-freezing storage unit 2000 can be maintained at −2° C. to −4° C., thereby keeping the meat in the non-frozen state. The user may store the meat in a frozen state at the same temperature as that of the freezing chamber 1100 without turning on the heaters 140 (see FIG. 9) or the thermoelectric element 11 (see FIG. 18). FIG. 22 is a side-sectional view showing a state where the non-freezing storage unit according to the first or second embodiment of the present invention is applied to the conventional refrigerator. The freezing chamber 1100 and the refrigerating chamber 1200 are arranged on the left and right sides in the longitudinal direction in the refrigerator 1000, and the non-freezing storage unit 2000 may be installed between shelves of the freezing chamber 1100, or the topmost shelf or the bottommost shelf of the freezing chamber 1100. An evaporator 1300 is located on a rear surface of the freezing chamber 1100 to exchange heat with the ambient air to produce the cool air. The cool air is introduced into the freezing chamber 1100 to maintain the refrigerator 1000 at a low temperature. The cool air heat-exchanged by the evaporator 1300 is introduced into the freezing chamber 1100 through a cool air vent 2420 via a duct 1600. When the freezing chamber 1100 is cooled by the cool air, as far as the heaters 140 (see FIG. 9) are not operated, the temperature in the non-freezing storage unit 2000 located in the freezing chamber 1100 is maintained to be the same as that of the freezing chamber 1100. When the heaters 140 are operated by the control of the control panel (not shown), the temperature in the non-freezing storage unit 2000 is maintained at −2° C. to −4° C. to store the meat in the non-frozen state. The non-freezing storage unit 2000 may be fixed to the freezing chamber 1100 such that only the drawer can be opened and closed in the forward direction, or the non-freezing storage unit 2000 itself may be separated from the freezing chamber 1100. When the non-freezing storage unit 2000 is manufactured to be separable from the freezing chamber 1100, preferably, terminals transmitting and receiving electricity are formed in the freezing chamber 1100 and the non-freezing storage unit 2000, respectively.

FIGS. 23 and 24 are views of a non-freezing storage unit according to a third embodiment of the present invention and a refrigerator including the same. The non-freezing storage unit according to the third embodiment of the present invention is installed in the refrigerator in the form of a so-called home bar. The refrigerator 1000 includes a refrigerating chamber 1300 storing food at a temperature range of about 2° C. to 10° C. and a freezing chamber 1400 storing food at a temperature of about −18° C., which are separated by a bulkhead. In addition, the refrigerator 1000 includes a refrigerating chamber door 1100 opening and closing the refrigerating chamber 1300, and a freezing chamber door 1200 opening and closing the freezing chamber 1400. The non-freezing storage unit 100 according to the third embodiment of the present invention is formed in the refrigerating chamber door 1100 or the freezing chamber door 1200. FIGS. 23 and 24 illustrate an example in which the non-freezing storage unit 100 is formed in the refrigerating chamber door 1100. A non-freezing storage unit door 130 is provided on the non-freezing storage unit 100 so that the non-freezing storage unit 100 can be opened and closed on the outside of the refrigerator 1000, when the refrigerating chamber door 1100 is closed. A casing 110 defining the non-freezing storage unit 100 may be separately formed and installed in the refrigerating chamber door 1100, or may be integrally formed with the refrigerating chamber door 1100. In FIG. 23, the non-freezing storage unit 100 is integrally formed with the refrigerating chamber door 1100. Hereinafter, for convenience's sake, the portion bent to define the non-freezing storage unit 100 is referred to as the casing 110. An insulation material 113 is filled in the casing 110 to insulate the non-freezing storage unit 100 from the refrigerating chamber 1300. Like the second embodiment of the present invention, a thermoelectric element 111 is installed on the inside of the casing 110. The thermoelectric element 111 may be formed in any one of the upper, lower and side portions of the casing 110. One or plural thermoelectric elements 111 may be provided. Moreover, a conductor 112 is installed in contact with the thermoelectric element 111 to effectively transfer a temperature change occurring in the thermoelectric element 111 into the non-freezing storage unit 100. With respect to the installation relation of the thermoelectric element 111, the conductor 112 and the casing 110, like the second embodiment, the thermoelectric element 111 may be installed in the casing 110 and the conductor 112 may be installed to cover the thermoelectric element 111, or the conductor 112 may be installed in the casing 110 and the thermoelectric element 111 may be installed on the conductor 112. Further, a display portion (not shown) and an operation portion (not shown) may be formed on any one of the upper, lower, left and right sides of the non-freezing storage unit 100, or may be formed on the non-freezing storage unit door 130. When the display portion (not shown) and the operation portion (not shown) are formed on the non-freezing storage unit door 130, preferably, a cable (not shown) applying power to the display portion (not shown) and the operation portion (not shown) and receiving a signal therefrom is guided through a hinge (not shown) of the non-freezing storage unit door 130.

Furthermore, preferably, a sensor 117 measuring a temperature in the non-freezing storage unit 100 and/or a sensor 114 measuring a temperature of food stored in the non-freezing storage unit 100 are installed in the non-freezing storage unit 100. The sensor 114 transfers the sensed temperature information to a control unit (not shown), and the control unit (not shown) controls the direction and intensity of the current applied to the thermoelectric element 111 according to the temperature information sensed by the sensor 114. With respect to the control unit (not shown), a separate control unit (not shown) irrelevant to a refrigerator main body may be provided in the casing 110 or the refrigerator main body to control the functions of the non-freezing storage unit 100, or a control unit (not shown) of the refrigerator main body may serve to control the functions of the non-freezing storage unit 100. The control unit (not shown) can control the functions of the non-freezing storage unit 100 using the same method as that of the first or second embodiment. 

1. A non-freezing storage unit, comprising: an outer casing with one open surface; a drawer which can be pulled out and detached through the open surface of the outer casing; a sensor located on one surface of the outer casing and sensing a temperature of food located in the drawer; a thermal conductive member installed on one surface of the drawer facing the sensor and transferring the temperature of the food in the drawer to the sensor; and a heater installed in the outer casing, wherein the non-freezing storage unit is located in a cooling space to store food in a non-frozen state at a temperature below 0° C.
 2. The non-freezing storage unit of claim 1, wherein an insulation material is filled in the outer casing.
 3. The non-freezing storage unit of claim 1, wherein the thermal conductive member comprises a metal plate located on a bottom surface of the drawer and receiving a temperature change of the food, and a contact point portion transferring the temperature change between the metal plate and the sensor.
 4. The non-freezing storage unit of claim 3, wherein the contact point portion is downwardly protruded from the bottom surface of the drawer.
 5. The non-freezing storage unit of claim 1, wherein a handle for use in pulling the drawer out is provided on one surface of the drawer corresponding to the open surface of the outer casing.
 6. The non-freezing storage unit of claim 5, wherein the handle comprises a grip portion and a hook portion moved in cooperation with the grip portion, and the outer casing comprises a hooked portion on which the hook portion is hooked.
 7. The non-freezing storage unit of claim 1, wherein a gasket for use in sealing up the inner space is provided on one surface of the drawer corresponding to the open surface of the outer casing.
 8. The non-freezing storage unit of claim 1, wherein the outer casing and the drawer comprise guide portions for guiding the movement of the drawer, respectively, and the guide portions guide the drawer so that the drawer can be located lower in the outer casing than during the movement, when the drawer is completely inserted into the outer casing.
 9. The non-freezing storage unit of claim 8, wherein, when the drawer is inserted into the outer casing and downwardly moved by the guide portions, the sensor and the thermal conductive member are brought into contact with each other.
 10. The non-freezing storage unit of claim 1, further comprising a fan installed in the outer casing and producing the flow of the air in the unit.
 11. The non-freezing storage unit of claim 1, wherein the heater comprises an upper heater installed on an inside top surface of the outer casing and a lower heater installed on an inside bottom surface of the outer casing.
 12. The non-freezing storage unit of claim 11, further comprising a sensor for sensing a temperature in the unit which is installed at an upper portion of the outer casing and senses a temperature of the air in the drawer.
 13. The non-freezing storage unit of claim 12, wherein a heating value of the upper heater is adjusted according to the temperature measured by the sensor for sensing the temperature in the unit, and a heating value of the lower heater is adjusted according to the temperature measured by the sensor.
 14. The non-freezing storage unit of claim 12, wherein the heating values of the upper heater and the lower heater are controlled so that the temperature in the inside upper portion of the unit can be higher than the temperature in the inside lower portion of the unit by about 1 to 2° C.
 15. The non-freezing storage unit of claim 12, wherein at least one of the upper heater and the lower heater comprises a plurality of individual heaters, at least one of the plurality of individual heaters is constantly operated, and the other individual heaters are turned on/off according to the temperature in the unit.
 16. The non-freezing storage unit of claim 1, further comprising a side casing located on a side surface of the outer casing and having a display portion and a button portion at the front.
 17. The non-freezing storage unit of claim 16, further comprising a control panel installed in the side casing, cooperating with the display portion, the button portion and the sensor, and controlling electric components in the unit.
 18. The non-freezing storage unit of claim 1, wherein the heater is a thermoelectric element having the flowing current and voltage controlled to adjust the temperature in the non-freezing storage unit.
 19. A refrigerator comprising: a non-freezing storage unit as recited claim 1; and a cooling space cooled by a freezing cycle and having the non-freezing storage unit therein.
 20. The refrigerator of claim 19, wherein a temperature in the non-freezing storage unit is maintained at about −2° C. to −4° C., raised to normal temperature when it is determined that the food has been frozen on the basis of a food temperature change sensed by a sensor, and lowered again to −2° C. to −4° C. to store the food. 